1. Field of the Invention
The present invention relates to recording media for ink-jet using kenaf paper as a substrate, and particularly to recording media for ink-jet, which can provide images having excellent water fastness.
2. Related Background Art
An ink-jet recording system is a system wherein minute droplets of an ink are ejected by any one of various working principles to apply them to a recording medium such as paper, thereby making a record of images, characters and/or the like, and is being quickly spread in various applications, for example, recording of various graphics including characters, and color images, and so on, because it has features that recording can be conducted at high speed and with a low noise, color images can be formed with ease, recording patterns are very flexible, and developing and fixing treatment are unnecessary.
Recording media used for such a recording system have come to be required to provide images having good water fastness in addition to ink absorption at high speed, high ink absorbing capacity, and the provision of images high in optical density and improved in image quality.
In order to satisfy such requirements, Japanese Patent Application Laid-Open No. 55-51583 discloses that a coating layer composed of amorphous silica and a polymer binder has good ink absorbency in printing with water-based inks and is hence suitable for use in high-density printing. With respect to recording media for ink-jet, which can provide images having good water fastness, the use of modified polyvinyl alcohol containing a silyl group is disclosed in Japanese Patent Application Laid-Open No. 10 61-134290, the use of a polycationic polymeric electrolyte in Japanese Patent Application Laid-Open No. 56-84992, a method of using a polyvalent metal salt in Japanese Patent Application Laid-Open No. 56-86789, a method of using at least one water-soluble metal salt having a divalent or still higher ionic valence and a cationic organic substance in Japanese Patent Application Laid-Open No. 60-67190, and a method of using silanol group-containing polyvinyl alcohol and a zirconium compound in Japanese Patent Application Laid-Open No. 6-32046. Further, Japanese Patent Application Laid-Open No. 7-1833 discloses a method of using a monoammonium compound as a water-proofing agent.
These known compounds and methods satisfy their intended ends, but still require improvement. From the viewpoint of, for example, improvement in the water fastness of images, it has been known that the addition of a cationic substance permits the improvement of the water fastness due to its ionic bonding to an anionic dye. However, in all the known recording media, they are only evaluated as to optical density by dipping the whole surfaces of prints in water to observe whether inks of the prints are redissolved out in water or not. From the viewpoint of practical use, a case where water is applied to a part of a print often occurs rather than a case where the whole surface of a print is dipped in water. In this case, bleeding at boundaries between a portion with which water has come into contact and a portion in no contact with water becomes a problem. In particular, even when inks are not redissolved out when the whole surface of a print is dipped in water, the bleeding may be observed in some cases when the print is brought into partial contact with water and dried. This is considered to be due to the fact that since penetration of water into a substrate proceeds over a longer period of time in the case of the partial contact with water compared with the case of the dipping in water, the bleeding of the print more markedly appears.
On the other hand, in the case where the coating layer composed of the amorphous silica and the polymer binder is formed on the surface of paper, the resulting recording medium is accompanied by many problems. For example, since the surface of paper is covered with the amorphous silica, the natural hand and feeling of paper is impaired, the surface thereof becomes powdery, and dusting occurs when it is folded or conveyed.